Suspected Bad Motor List

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Charles_McG

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Thanks for clarifying as I had read cracked cores were a problem.
I've read the same thing - but usually about F-H BP beasts no longer in production. The 29mm Estes E-F BP motors seem to get fewer reports than the 24mm Es. Maybe because fewer are flown - but we can't tell that from public data.

Some stories told about motor vulnerabilities are just factoids. They look reasonable, but aren't proven. Like physical shock to a motor. Tested. Smaller BP motors are tough. The weakness turned out to be thermal cycling.

As the energy involved increases I would expect there to be more problems cropping up.
Isn't "rocket science" always about trying not to explode with failures far from unknown?
I don't know that's true (problems proportional to impulse). There's more energy to make a bigger consequence. But I don't know about actual failure rate. Maybe there are factors that co-vary with impulse - like novelty of a new motor size (I'm using novelty as the inverse of experience), complexity of motor prep, go-fever, etc. that make it seem that way.
 

djs

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I
Some stories told about motor vulnerabilities are just factoids. They look reasonable, but aren't proven.
It makes me wonder what testing the motor mfgs do on their motors. Obviously test burns to verify impulse, thermal tests on cases, etc. But do they test motors to destruction? I'm thinking about things like extreme temperatures, under heavy thrust, after an impact (dropped from 6' onto a concrete floor and then tested), thermal cycling, etc?
 

shreadvector

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Ok, help me out here.
Isn't the problem due to the black powder propellant cracking and this is far more likely
on the larger sizes?
Is this a problem with composite propellant?

Cracked BP grains is almost NEVER the problem. It was the problem for select motors or batches, such as the FSI E60, F100 and the Year X Estes C5 motors. The C5 had cracks originate in the centerbore after they cured ("cured" = dry out since they are pressed with damp propellant).

Most catos of motors, such as the long ago D12 issues of the 1970s and the more recent E9 issues are a simple weakening of the mechanical bond of the propellant to the casing wall. If the nozzle pops, and the propellant stay inside, that is the nozzle to casing bond failing. If the nozzle bond is normal, when the flame front reaches the wall of the casing, it can propagate up the sides of the propellant grain - resulting in a HUGE overpressure. This will blow the grain out the top like a Roman Candle. It can also blow the nozzle as the pressure gets very high. IF the delay train is bonded really good, and the nozzle stays bonded good, then the excess pressure has nowhere to go and the casing splits (pretty loud). That would happen with some of the Estes BP E15 motors and some of the Year X C5 motors.

Now, how does the flame get to the propellant wall "too soon" after ignition and what makes the propellant to casing bond fail?
Temperature Cycling. The cardboard and propellant expand when they get hot (sitting in a hot garage/car/USPS truck/etc.). The propellant is nice and solid and it expands in length and diameter. It stretches the cardboard casing which is made of wood fibers with some glue. When the motor cools, the propellant returns to it's original size, but the casing may not shrink back at the same rate or it may stay slightly stretched. This can compromise the propellant to casing mechanical bond, which allows the flame to propagate up the inside.

The nozzle to propellant interface also expands at different rates, so there is a small crack that forms around the outside of the nozzle to propellant interface. This allows the flame to reach the wall shortly after ignition and before it normally would get there (at the time of peak thrust at the top of the thrust-time curve).

I tested hundreds of D12-5 motors to help confirm temperature cycling was an issue and to help define the exact failure mode.

To crack the grain, you need to lay the motor on a concrete floor and hit the motor with a large hammer.

From what I've heard, Estes worked hard to get their casing suppliers to produce the highest quality casings to meet their specifications to help reduce/eliminate most of the problems seen in the D12 in the 1970s.

I suspect that most of the 'spit nozzle' failures of the current generation of motors are from the clay material properties. The current clay is what I call "Strong Like Ox". it is WAY better than the "Poopy Clay" used back around the release of Star Wars Episode 1 and the mass of rockets and motors produced at the time. That "Poopy Clay" was not good.
 

beantownJPL

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A10-3T (two motors from the same pack) - LOT#: B180619

One of them blew out both ends of the motor, spectacular burning fuel pellet thrown about 15' into the sky, destroyed model. The second one just blew out the nozzle.
 
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Charles_McG

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CTI Pro29-3G G33MY
Apr 30 2018
Mine today and I know of 3 others from 2018.
Resulting pieces look a lot like the Pro38-1G too-fast-starter pieces.
 

gna

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E12-6 Cato. Lot D 19 06 19. Didn't get a shot of the CATO, unfortunately.View attachment 389099 View attachment 389100 View attachment 389101
I emailed Estes, and they sent me 3 new E12-6s. However, they were they same Lot: D 19 06 19. I was at a club launch yesterday, and another flier had 2 packs of E12-6s with the same lot code.

The other flier's first flight CATOd, and so did mine. He tried the other pack in a rocket he "didn't care that much about," and it CATOd, too. He then taped another E12-6 to a rod for a static test:
The blast plate was dented from the nozzle.
Be careful with this lot!
 
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Rick B

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I have two packs of the E12-6s, Lot: D 19 06 19. I shot two motors this weekend without an issue. Not sure if I should continue to roll the dice or ... I've never had a CATO yet so perhaps it's a new opportunity. ;-)
 

Rocketjunkie

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2 J145 catos at the Camden launch Saturday. Both instant BOOM on the pad, both dated March 18, 2016.
 

Red7Fifty

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Great Effort.....Just when it was about to launch...I thought...what if it CATOed?
 

deangelo54

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Of the five Estes E12-4 engines I used two have CATOed. One of the CATOs destroyed a rocket. The date code is D 19 08 19. I have filed MESS reports and contacted Estes.
 

John Taylor

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Now I'm nervous, I am scheduled to fly an old classic Maxi Force I've had for 24 years on a three motor cluster loaded with three Estes E motors. How worried should I be?
I really dont want to lose the rocket. At this point I dont have info on the lot number. I dont know where it would be located. I threw away the packaging and I had to sand a little off the surface of the motor to fit comfortably in the motor mount obliterating the writing.
 

rharshberger

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Now I'm nervous, I am scheduled to fly an old classic Maxi Force I've had for 24 years on a three motor cluster loaded with three Estes E motors. How worried should I be?
I really dont want to lose the rocket. At this point I dont have info on the lot number. I dont know where it would be located. I threw away the packaging and I had to sand a little off the surface of the motor to fit comfortably in the motor mount obliterating the writing.
If you don't want to risk the rocket to a higher risk of CATO'ing motors then fly it on something else.
 

Jacob Ritzke

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This is why I don't ever fly Estes E motors, they always seem to have a much higher CATO rate.
 

Matt_The_RocketMan

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Great Effort.....Just when it was about to launch...I thought...what if it CATOed?
I had that exact same moment happen to my rocket, the engine went the apposite direction of the rocket and somehow the ejection charge went off the same time as the initial ignition. Thus leading to what looked like an explosion but all what happened was the engine blew up the bottom half of the rocket as it traveled upwards. Initially the rocket went off in a big BOOM! Estes always is spot on with there warranty...
 

John Taylor

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Now I'm nervous, I am scheduled to fly an old classic Maxi Force I've had for 24 years on a three motor cluster loaded with three Estes E motors. How worried should I be?
I really dont want to lose the rocket. At this point I dont have info on the lot number. I dont know where it would be located. I threw away the packaging and I had to sand a little off the surface of the motor to fit comfortably in the motor mount obliterating the writing.
Decided to abandon using the Estes F engines. Going with three Economax F44 motors. Usimg augmented igniters. Hopefully all three light. Should be interesting.
 

shreadvector

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I am encouraging everyone in my local NAR Section to use up all of their E9 motors and record the results.
We had a launch on 21 and 29-Sep and flew (14) E9 motors. Only one failed. here is the data I have:

FLEW GREAT:
(1) E9-6 (no date code written down by flyer)
(1) E9-4 (no date code written down by flyer)
(1) E9-6 (A 06 08 10 1)
(1) E9-4 (A 04 14 11)
(2) E9-4 (A 06 22 12)
(6) E9-4 (A 09 15 14)
(1) E9-4 (A 07 25 16)

Failed a fraction of a second after ignition:
(1) E9-4 (A 06 22 12)

I have 6 or 7 packs of A 09 15 14 left. Plus whatever everyone else has.

The E9-4 with adapter worked great in the Majestic kit.
 

shreadvector

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Please "record the results" using this form:
http://motorcato.org/MESSForm.aspx

Discussions about bad motors are great, but let's collect as much data as possible using the existing mechanism.
I aksed people to record the results - meaning put the date code on their flight cards - so that we could show that very few actually fail compared to the large numbers actually launched.

Of course they file a M.E.S.S. report. There should only be one from Martin Bowitz. I just IM'd him and he has the casing and it's on his "To Do" list. He will do it.

I think he is waiting until after the launch tomorrow in case he has more....
 

shreadvector

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I am encouraging everyone in my local NAR Section to use up all of their E9 motors and record the results.
We had a launch on 21 and 29-Sep and flew (14) E9 motors. Only one failed. here is the data I have:

FLEW GREAT:
(1) E9-6 (no date code written down by flyer)
(1) E9-4 (no date code written down by flyer)
(1) E9-6 (A 06 08 10 1)
(1) E9-4 (A 04 14 11)
(2) E9-4 (A 06 22 12)
(6) E9-4 (A 09 15 14)
(1) E9-4 (A 07 25 16)

Failed a fraction of a second after ignition:
(1) E9-4 (A 06 22 12)

I have 6 or 7 packs of A 09 15 14 left. Plus whatever everyone else has.

The E9-4 with adapter worked great in the Majestic kit.

More data:

FLEW GREAT:

(4) E9-4 (A 09 15 14)
(1) E9-4 (A 01 12 16)

(3) E12-4 (no date codes recorded because we almost NEVER see a cato for the E12 motors. They flew GREAT).
 

deangelo54

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I just looked at the Suspected Bad Motor List under the Estes E12 and see that I may have provided the wrong date code. I reported D 19 08 19. After zooming in on the photos I took of the failed engine I see that the date code should be D 19 06 19. On the engine casing the 6 looks a lot like an 8. Hopefully the list can be updated.
 

lakeroadster

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I just looked at the Suspected Bad Motor List under the Estes E12 and see that I may have provided the wrong date code. I reported D 19 08 19. After zooming in on the photos I took of the failed engine I see that the date code should be D 19 06 19. On the engine casing the 6 looks a lot like an 8. Hopefully the list can be updated.
Updated List. There was already a D 19 06 19 on the list... so I just deleted the D 19 08 19 entry. Thanks for bringing this to our attention.
 

shreadvector

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More data:

FLEW GREAT:

(4) E9-4 (A 09 15 14)
(1) E9-4 (A 01 12 16)

(3) E12-4 (no date codes recorded because we almost NEVER see a cato for the E12 motors. They flew GREAT).

More data.

No catos. All flew GREAT!

(1) E9-4 (A 03 30 17)
(1) E9-4 (A 09 15 14)
(1) E9-4 (he did not write down date code on flight card)

(2) E12-6 (no date codes recorded because we almost NEVER see a cato for the E12 motors. They flew GREAT).
 

Chris Brewer

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I have launched 4 E12-6 from 3 different lots and 2 resulting cato’s. The 1st one Estes replaced the motor and Big Daddy kit. The 2nd was this weekend and motor came from the replacement motors Estes sent. Rocketarium Black Brant VB. The motor mount was blown apart, baffle blown out the end and body tube wrinkled in several places. Both successful flights were from an older lot. I am seriously considering not using these motors again.
https://photos.app.goo.gl/UZqU2hnVqa8RpEah9
 
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